Rotary drum furnace for melting metals



C. BRACKELSBERG ROTARY DRUM FURNACE FOR MELTING METALS Filed March 14, 1950 Ill 7 BY W ATTORNEYS Patented a. '4, 1932 PATENT; OFFICE CARL BRAGKELSBERG, OF MILSPE, GERMANY ROTARY DRUM FURNACE FOR .MELTING HETALB Application filed March 14, 1980, Serial No.

v This invention relates to rotary drum furnaces of a type particularly adapted for melting metals such as iron alloys and in which the charge is agitated by the rotation of the drum and the heated upper surface of the drum is continually being carried beneath the charge.

As one important feature of the present invention the axis of the heating chamber is disposed at an angle to the axis of the rotation of the drum whereby as the drum is rotated the charge is caused to move back and forth in the direction of the length of the chamber at the same time it is being agitated by the rotary movement of the wall. As a further important feature the charge to be heat treated is delivered through an inclined chute or conduit which may be rigidly supported and form a fairly gas tight 90 seal with the furnace and which serves as an outlet conduit for the combustion gases whereby the charge is preheated during its delivery into the furnace.

I As a further important feature the drum is subdivided into two chambers spaced apart axially of the drum and by means of an annular partition or dividing wall whereby the portions of the charge in the two chambers may be kept separate except insofar as the metal continuously or intermittently flows from one over the partition wall into the other. The first chamber serves for preheating and melting the charge, while the second serves for the thorough mixing and superheating of the melted mass delivered thereto from the first chamber.

As a further important feature the first chamber is preferably substantially conical with its larger end adjacent to the partition or dividing wall so that as the material melts in the first chamber it flows to the larger end and. a comparatively small amount of the molten matter is retained in the preheating and melting chamber. By means of my invention an economical melting and a continuous operation is'made possible. It is merely necessary to stop the rotation for a short time at given intervals to draw off the molten iron for foundry use. If necessary the apparatus may be so de- 435,712, and in Germany October 29, 1929.

signed that the liquid may be drawn off while the furnace is in rotation. 7 I Reference is to be had to the accompanymg drawing in which the single figure shows a vertical central lon "tudinal section through a furnace embo ying the various im ortant features of my invention above re erred to and more particularly set forth hereinafter.

In the construction illustrated there is rovided a drum 0 of metal with a lining o fire resistantmaterial and which is so formed as to give to the chambers within the drum the de sired shape, size and proportions. The outer shell or drum proper is provided with annular reinforcing ri s a which serve as tracks for engagement with the usual supportin rollers d whereby the drum may be rotate about its longitudinal axis.

As means for rotating such a drum are well lmown in the art and form no portion of my invention I have not illustrated any such means, but it will be understood that suitable means are provided for effecting the rotation at the desired speed. Merely as 7: an example the drum may be provided with an annular gear meshing with a pinion driven from a suitable source of power.

The interior of the drum is lined with a refractory mass 7 which is so formed and so 4 proportioned as to give to the interior of the drum the construction forming the important features of my invention. As shown this refractory mass is designed to provide two chambers g and h by means of an annular wall or bridge g-intermediate of the ends of the drum.

The drum is heated by means of a suitable burner 71 which delivers the fuel and combustion supporting air axiall of and directly into the chamber g. lthough any suitable fuel may be employed I preferably use coal dust. At the opposite end of the chamber h the drum has a centrally disposed opening for the admission of the charge and for the escape of the combustion gases.

' The drum may be provided with a neck which engages a wall m to form a fairly gas tight joint and this wall also serves to support an inclined chute or conduit 70 through which the charge'may be delivered to the furnace and through which the combustion ses may escape. This chute thus serves a ouble purpose in that it permits the feed-' ing of the furnace by avity and the preheating of the charge byt e ases whlch pass out in a counter direction. s the chute and the furnace both engagethe stationary wall m the chute may be rigidly supported and does not rotate.

The chamber 1:. is substantially conical in form with its largest portion near the center of the drum, that is adjacent to the artition or annular baflie g. The inclined we 1 of this chamber thus causes the preheating of the mass as it travels down the incline toward the larger end and its rate of travel may be such that the melting process is substantially completed by the time the charge reaches the larger portion. The molten metal collects in front of the baffle or partition 9 and due to the conical shape of the chamber k the said chamber stores only a comparatively small amount of the molten metal. As fast as the metal melts it flows from the partition 9 into the second chamber 9.

The chamber 6 has its axis at an angle to the axis of rotation so that the molten metal is caused to flow back and forth during the rotation of the furnace. With the parts in the position shown in the drawing the metal will tend to accumulate toward the left hand end of the chamber, while when the drum is rotated through 180 the metal will have flowed back toward the end adjacent the partition 9. This back and forth movement tends to thoroughly. agitate and mix the charge and this mixing action is in addition to that effected by the rotation of the drum. The rotation serves to effect a more uniform heating of the charge as the wall of the chamber above the molten metal becomes directly heat- .ed by the combustion gases and is carried beneath the charge as thedrum rotates.

The second chamber 9 is equipped with a tap hole 1" from which the molten metal ma be d'awn as needed for use or at any time des1re The chamber his likewise provided with a tap hole 8 in order to permit emptying of this chamber if necessary.

By means of my improved construction economical operation is accomplished because of the reheating of the charge in the chute k, the urther preheating and melting in the chamber h, the delivery of only molten metal to the chamber 9, and the thorough and effective heating and mixing in the chamber g. Thus a very high grade iron is obtained and the combustion heat efiiciently utilized.

It will of course be obvious that various changes may be made in the construction illustrated without departing from the scope of my invention and that certain features of the invention, such for instance as the inclined preheating chute and the inclination of the axis of the chamber 9, may be utilized in se arate constructions, and that the drum ma e divided into more than two chambers if esired.

As previously noted the fuel may be of any suitable character, but preferably coal dust is employed, and the volume and velocity of the combustion supportin air and the carrier gases are such that t e fuel burns while in suspension and the ashes are conveyed to and swept from the outlet end along with the combustion gases so that they do not settle upon or contaminate the charge.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A rotary furnace for melting metals includinga drumhaving an annular wall inter mediate of the ends thereof dividing the interior of the furnace into chambers, and concentrically disposed" with respect to the axis.

of rotation of the furnace, means for delivs ering a charge to the outer extreme end of one chamber, and means for delivering combustion gases to the opposite end of the other chamber, the chamber in which the charge is delivered being substantially conical and formed with its larger end adjacent to said annular wall. j,

2. A rotary furnace for melting metals including a drum having an annular Wall intermediateof the ends thereof dividing the interior of the furnace into chambers, and concentrically disposed with respect to'the axis of rotation of the furnace means for delivering a charge to the outer extreme end of substantially conical form, an inclined chute juxtaposed to the smaller end of the chamber and serving for the delivery of the charge and for the escape of gases of combustion,- said drum having a tap hole at the larger end.

4. A rotary furnace for melting metals, including a drum having two chambers disposed in tandem, and communicating with each other, one serving for the preheating and melting of the charge, and the second for the mixing and superheating of the mol ten mass flowing thereto from the preheating chamber, said preheating chamber being substantially conicalin shape, andformed with its larger end adjacent the superheating chamber, and said superheating chamber having its axis inclined to the axis of the drum, whereby'the molten charge is caused y cluding a drum having a chamber therein of to move back and forth longitudinally during the rotation ofthe drum.

5. A. furnace for melting metals and rotatable about a horizontal axis, including a drum having a peripheral wall concentric with said axis, and having a chamber therein, the wall of said chamber being of varying thickness circumferentially to form the chamber with its axis inclined in respect to the axis of the drum, a second chamber disposed in tandem with respect to said first mentioned chamber, communicating therewith, and formed substantially conical with its larger end disposed adjacent said first mentioned chamber, means for delivering combustion gases from the outside end of said first mentioned chamber, and means for delivering the charge to the outside end of the conical chamber.

6. A rotar furnace for melting metals,

including a rum having end walls and an inwardly extending flange intermediate the ends forming two chambers in tandem, one serving as a premelting chamber and the other as a final melting chamber, a burner for delivering a flame 1nto said furnace at the outer end of the last mentioned chamber and an inclined conduit at the outer end of i the first mentioned chamber, said conduit servin for the delivery of the metal to be melte and the delivery of the combustion ases from the furnace, whereby the metal in entering is preheated before entering the furnace.

7. A rotary furnace for melting metals, including a cylindrical drum having a peripheral wall concentric with the axis of rotation of the furnace, and a refracto lining havin an opening concentric wit the axis of sai lining, and forming a cylindrical chamber of uniform cross-sectional area through the length of the main portionthereof, the axis of said chamber being inclined with respect to the axis of rotation of the furnace, whereby upon the rotation of said furnace, the molten metal will flow back and forth lengthwise of said chamber alon straight line elements of the inner surface 0 said lining.

Si ed at (.lolo ne German this 28th da of Fe h ruary, A. 1 930. y

CARL BRACKELSBERG. 

